Next week we will be focussing on subtraction. The first thing we need to know is how you do subtraction at the moment, so here are some questions for you to have a go at.

83 – 57 382 – 155 444 – 186 502 – 245 1625 – 717 3007 – 1999

Do them in your learning log and post your answers on the blog. Then watch these videos. They explain some subtraction methods which you may have used in school. What do you think? Do you have any questions?

https://www.youtube.com/embed/Y6M89-6106I

https://www.youtube.com/embed/BkzoUfyAXDU

https://www.youtube.com/embed/y_v7brcfW-Q

There are many ways of doing subtraction and we have to find those that work consistently for us. You need one “go to” method that you would use for most questions because it always works. There may then be other questions that you use other methods for because it is more efficient.

Done in school

Have you watched the videos?

1) 83-57 = 26

2) 382-155 = 227

3) 444-186= 258

4) 502-245= 257

5) 1625-717= 908

6) 3007-1999= 1008

I used column subtraction to work out the questions.

Which question did you find the most difficult?

I found question 4 and 6 hard. With question 4 at first I didn’t know how to borrow 1 from the 0 to take across to the 2 but then my mum showed me that you need to cross out the 50 and then borrow 1 (to make it 49) and place it with the 2 to make 12. With question 6 I wasn’t sure how to borrow but then I remembered that it’s almost like question 4 and I needed to cross out the 300 and borrow 1 (to make it 299) to make 17.

I used column subtraction because when I tried to partition it didn’t work because you can’t do (for example) 3-7.

1. Answer: 26

2. Answer: 227

3. Answer: 258

4 Answer: 257

5. Answer: 908

6.Answer: 1,008

Which question did you find the most difficult?

On the first video I kind of got what they were trying to say .I also knew what the second video told me.But the last video was a problem because I didnt really get the replacing numbers part or (borrowing).

That’s fine Saira. The idea is that some videos suit you better than others. Personally, I think that “borrowing” should be called “exchanging”. This part is in all of the videos if you look closely.

1 26

2 227

3 258

4 909

5 1,000

used a different method

1) 83-57=26

2) 382-3=227

3) 444-186=258

4) 257

5) 908

6) 3007-1999=1008

I think that the most difficult one was the last one because it had the most digits.

I have done these at school.